This disclosure relates to the field of vertebral implants, in particular to corpectomy cages or intersomatic cages, designed to replace a vertebral segment, that is, all or part of at least one vertebral body and/or of at least one intervertebral disc. The disclosure relates more particularly to a vertebral implant, in particular to corpectomy, at least one vertebral fastening device of such an implant and implant instrumentation.
A problem in the field of vertebral implants and especially of corpectomy cages relates to deployment of an implant capable of replacing a vertebral segment, sometimes large in size, at least in height, for a corpectomy cage, since the vertebral segment can correspond to any or part of at least one vertebral body and/or at least one intervertebral disc. In fact, some pathologies, especially cancer conditions, result in degradation of vertebral bodies (in part or in totality) and/or of intervertebral discs. It is necessary to replace damaged vertebral segment(s) by an implant of considerable height. Also, it is often preferable to be able to modulate the height of the implant during surgery, since ablation of the damaged structures generally needs distraction of vertebrae to restore a physiological height (or less pathological) on the treated vertebral segment and this height varies as a function of the extent of lesions (to insert the implant between healthy tissues).
A problem associated with the problem of height of implants relates to the stabilization of the implant against the vertebral structures between which it is inserted. The necessary distraction is often incompatible with numerous stabilization solutions, such as notches on the contact surfaces of the implant, since these notches require additional distraction for insertion of the implant to be made. Also, anchoring the implant is generally preferable to simple notches that generally only limit the risks of movement but guarantee no reliable immobilization.
Solutions are known from prior art, especially for corpectomy, such as expansible cages in situ, generally comprising a body including mobile elements providing the vertebral contact surfaces and boosting the height of the implant once the latter is inserted between the vertebrae. These solutions have disadvantages of being based on generally complex and expensive mechanisms which often embrittle the implant and/or the vertebrae, since the distraction achieved by the implant during its expansion often does not test the effort exerted (such that implants sag sometimes in the vertebrae). Also, they often offer reduced graft space, disallowing the addition of a bone graft or adequate substitute. Also, these solutions have a low expansion ratio (1/3) and therefore generally require that the compressed implant be of a size already big enough so that its size is satisfactory when it is expanded and the design of these cages often means relaxing the distraction to allow their insertion into the vertebral segment. Finally, these types of expansible cages are often incompatible with notches or teeth for stabilization (as the latter reduce the capacity of real distraction, impair positioning and risk embrittling adjacent vertebral structures) and/or with anchoring (as the cages generally do not offer a sufficiently wide structure to retain anchoring means). Also, anchoring via screws can prove fastidious to be put in place and need an excessively invasive approach.
A final problem, often linked to disadvantages of solutions from prior art, relates to ablation of the implant which is generally impossible or difficult.
In this context, it is interesting to propose various embodiments for an implant that may be easily implantable, robust and reliable, adaptable to different sizes, limiting risks of embrittling adjacent vertebral structures, offers easy ablation and anchoring in the vertebral bodies without compromising final positioning and without the need for distraction superior to that required for insertion of the implant.